Gekkan Go World, after a shaky start now possibly the world's best go magazine, normally begins with in-depth coverage of a major title game. But the February 2006 edition starts with an instructional article. They knew they had something big!
It's long article by Yuki Satoshi, left. He's a Kansai Ki-in pro and this is a Nihon Ki-in magazine. That's point 1. Point 2: despite an unpreposessing title - "Don't be afraid of kos" - it's one of the meatiest examples we've seen of how pros operate as opposed to how they normally tell amateurs to operate. Gekkan Go World has recently had a string of similarly meaty articles by Kobayashi Satoru, and O Meien has for some time been offering articles, books and lectures with novel insights into the pro mind. But they are often about fusekis. Yuki's article dips into the muddy waters of ko fights.
As a taster, look at this ko. Make sure you understand it is a two-stage ko (nidan kou) and try to count its value in deiri ("swing") terms - Sensei's Library will offer help here if you need it (count the position after Black wins and the position after White wins, and add the two values together).
You should get a value of about 36 points, and you should note also (if you want to think like a pro) that whoever wins this ko, the result has little immediate impact on the surrounding position, and so there is no extra profit to be gained at this stage.